Through the Interface

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.BoundaryRepresentation;

using Autodesk.AutoCAD.DatabaseServices;

using Autodesk.AutoCAD.EditorInput;

using Autodesk.AutoCAD.Geometry;

using Autodesk.AutoCAD.Runtime;

using System;

 

namespace BrepTest

{

  public class Commands

  {

    [CommandMethod("PISO")]

    public void PointInSolid()

    {

      var doc = Application.DocumentManager.MdiActiveDocument;

      var db = doc.Database;

      var ed = doc.Editor;

 

      try

      {

        // Select Solid3d

 

        var peo = new PromptEntityOptions("\nSelect a 3D solid");

        peo.SetRejectMessage("\nMust be a 3D solid.");

        peo.AddAllowedClass(typeof(Solid3d), true);

 

        var per = ed.GetEntity(peo);

        if (per.Status != PromptStatus.OK)

          return;

 

        using (var tr = db.TransactionManager.StartTransaction())

        {

          // Open the selected Solid3d

 

          var sol = tr.GetObject(per.ObjectId, OpenMode.ForRead) as Solid3d;

          if (sol != null) // Should always be true

          {

            // Create the sub-entity path to it

 

            var ids = new ObjectId[] { per.ObjectId };

            var path =

              new FullSubentityPath(

                ids, new SubentityId(SubentityType.Null, IntPtr.Zero)

              );

 

            // Create a Brep from the path

 

            using (var brep = new Brep(path))

            {

              while (true)

              {

                // Select point

 

                var ppr = ed.GetPoint("\nSelect a point");

            

60;   if (ppr.Status != PromptStatus.OK)

                  break;

                var pt = ppr.Value;

 

                // 1) Check point containment w.r.t selected solid

 

                var pc = new PointContainment();

                using (var brepEnt = brep.GetPointContainment(pt, out pc))

                {

                  ed.WriteMessage("\nPt {0}: {1}", pt, pc);

                }

 

                // 2) If Outside, check whether the solid is "below":

 

                if (pc == PointContainment.Outside)

                {

                  // Fire a -Z Ray from the point to find if it hits the Brep

 

                  var ray = new Ray3d(pt, -Vector3d.ZAxis);

                  var hits = brep.GetLineContainment(ray, 1);

 

                  if (hits == null || hits.Length == 0)

                  {

                    ed.WriteMessage("\nSolid is NOT below point.");

                  }

                  else

                  {

                    ed.WriteMessage(

                      "\nSolid IS below point, distance = {0}",

                      pt.DistanceTo(hits[0].Point)

                    );

                  }

                }

              }

            }

          }

          tr.Commit();

        }

      }

      catch (System.Exception ex)

      {

        ed.WriteMessage("Error: {0}\r\n at {1}", ex.Message, ex.StackTrace);

      }

    }

  }

}